The contain property allows an author to indicate that an element and its contents are, as much as possible, independent of the rest of the document tree. This allows the browser to recalculate layout, style, paint, size, or any combination of them for a limited area of the DOM and not the entire page. This property is useful on pages that contain a lot of widgets that are all independent as it can be used to prevent one widget's CSS rules from changing other things on the page.
On mobile devices, the text-size-adjust property allows Web authors to control if and how the text-inflating algorithm is applied to the textual content of the element it is applied to.
There are several properties you can look at in order to determine the width and height of elements, and it can be tricky to determine which is the right one for your needs. This article is designed to help you make that decision.  Note that all these properties are read-only.  If you want to set the width and height of an element, use  width and height; or, the overriding min-width and max-width, and min-height and max-height properties.
The HTML Small Element (<small>) makes the text font size one size smaller (for example, from large to medium, or from small to x-small) down to the browser's minimum font size.  In HTML5, this element is repurposed to represent side-comments and small print, including copyright and legal text, independent of its styled presentation.